Postoperative Fever

Article Author:
Tony Abdelmaseeh

Article Editor:
Tony Oliver

Editors In Chief:
Stephen Leslie
Karim Hamawy

Managing Editors:
Avais Raja
Orawan Chaigasame
Carrie Smith
Abdul Waheed
Khalid Alsayouri
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Beenish Sohail
Nazia Sadiq
Hajira Basit
Phillip Hynes
Komal Shaheen
Sandeep Sekhon

1/23/2019 2:26:48 PM


Post-operative fever is defined as a temperature greater than 38 C (or greater than 100.4 F) on 2 consecutive post-operative days or greater than 39 C (or greater than 102.2 F) on any postoperative day. Knowledge of differential diagnosis, as well as a systematic approach, proves useful in narrowing down the differential diagnosis and instituting proper management.[1][2]

Fever as a manifestation of sepsis should be promptly identified and managed appropriately to lower mortality rates in such cases.


Timing strongly influences etiology.

  • Underlying conditions (e.g., immunosuppressed patients) may have a reduced inflammatory response or reduced fever while at the same time having a serious infection.
  • Differential diagnosis includes infectious (e.g., nosocomial or surgical site infections) and non-infectious (e.g., Deep vein thrombosis, pulmonary embolus, myocardial infarction, drug-related, transfusion-related, endocrine-related for example adrenal insufficiency or thyroid storm) causes.
  • Fever is more likely to be due to infection as the time interval following surgery increases.
  • Fever in patients may have more than one cause at the same time, and infectious and non-infectious causes may coexist.


Post-operative fever is very common. The exact incidence of postoperative fever is not known, but the numbers are high. Estimates from different surgical procedures reveal that fever occurs early in the postoperative period anywhere from 20% to 90% of patients. In the majority of these cases, the fever occurs on the first or second day after surgery and has been linked to atelectasis. Postoperative fever is known to occur after all types of surgical procedures, irrespective of the type of anesthesia. The fever also occurs in children and both genders. Postoperative fever can occur after minor surgical procedures but is rare and depends on the type of procedure. Overall, both abdominal and chest procedures result in the highest incidence of postoperative fever.[3][4]


Systemic Inflammatory Response Syndrome (SIRS):

Four criteria that include:

  • Temperature greater than 38 C or less than 36 C
  • Heart rate greater than 90 beats per minute
  • Respiratory rate greater than 20 per minute
  • White blood cell count greater than 12 x 10/L or less than 4 x 10/L

Two of the 4 criteria are needed to identify a patient with SIRS.

Two SIRS criteria plus a suspected source of sepsis to diagnose sepsis.

  • Sepsis plus organ dysfunction is consistent with severe sepsis
  • Severe sepsis plus refractory hypotension (refractory to fluid resuscitation) is consistent with septic shock

Signs of Organ Dysfunction

  • Systolic BP less than 90 mm Hg or mean arterial pressure less than 65 mm Hg.
  • Drop in BP greater than 40 mm Hg (especially in hypertensive patients)
  • Lactate greater than 2 mmol/L
  • Urine output less than 0.5 mg/kg/hr for 2 consecutive hours
  • Drop in Glasgow coma scale (GCS) or abbreviated mental test scores

History and Physical

Immediate Fever

Fever occurs immediately after surgery or within hours on postoperative days (POD) 0 or 1.

  • Malignant hyperthermia: high-grade fever (greater than 40 C), occurs shortly after inhalational anesthetics or muscle relaxant (e.g., halothane or succinylcholine), may have a family history of death after anesthesia. Laboratory studies will reveal with metabolic acidosis and hypercalcemia. If not readily recognized, it can cause cardiac arrest. The treatment is intravenous dantrolene, 100% oxygen, correction of acidosis, cooling blankets, and watching for myoglobinuria.
  • Bacteremia: High-grade fever (greater than 40 C) occurring 30 to 40 minutes after the beginning of the procedure (e.g., Urinary tract instrumentation in the presence of infected urine). Management includes blood cultures three times and starting empiric antibiotics.
  • Gas gangrene of the wound: High-grade fever (greater than 40 C) occurring after gastrointestinal (GI) surgery due to contamination with Clostridium perfringens; severe wound pain; treat with surgical debridement and antibiotics.
  • Febrile non-hemolytic transfusion reaction: Fevers, chills, and malaise 1 to 6 hours after surgery (without hemolysis). Management: Stop transfusion (rule out hemolytic transfusion reaction) and give antipyretics (avoid aspirin in the thrombocytopenic patient).

Acute Fever

Fever occurs in the first week (1 to 7 POD).

  • POD 1 to 3: atelectasis: After prolonged intubation, the presence of upper abdominal incision, inadequate postoperative pain control, lying supine. Should be prevented by incentive spirometry, semi-recumbent position, adequate pain control, early ambulation. Clinically may be asymptomatic or with increased work of breathing, respiratory alkalosis, chest x-ray with volume loss. Treatment includes spirometry, chest physiotherapy, semi-recumbent position (improves expansion of alveoli by preventing pressure from intra-abdominal organs on the diaphragm and hence improving functional residual capacity)
  • POD 3: Unresolved atelectasis resulting in pneumonia (respiratory symptoms, Chest x-ray with infiltrate or consolidation, sputum culture, empiric antibiotics and modify according to culture result and sensitivity), or development of urinary tract infection (urine analysis and culture, treat with empiric antibiotics and modify according to culture result and sensitivity)
  • POD 5: Thrombophlebitis (may be asymptomatic or symptomatic, diagnose with Doppler ultrasound of deep leg and pelvic veins and treat with heparin)
  • POD 7: Pulmonary embolism (tachycardia, tachypnea, pleuritic chest pain, ECG with right heart strain pattern (a low central venous pressure goes against diagnosis), arterial blood gas with hypoxemia and hypocapnea, confirm diagnosis with CT angiogram, and treat with heparin, if recurrent pulmonary embolism while anticoagulated with therapeutic INR, Inferior vena cava filter placement is the next step
  • POD 7 (5 to 10): Wound infection: Risk increases if the patient is immunocompromised (e.g., diabetic), abdominal wound, duration of surgery greater than 2 hours or contamination during surgery. Signs include erythema, warmth, tenderness, discharge. Rule out abscess by physical exam plus ultrasound if needed. If an abscess is present, drainage and antibiotics are needed. Prevention is by careful surgical technique and prophylactic antibiotics (e.g., intravenous cefazolin at the time of induction of anesthesia as well as postoperatively if needed)

Subacute Fever

Fever occurs between postoperative weeks 1 and 4.

  • POD 10: Deep infection (pelvic or abdominal abscess and if abdominal abscess could be sub-hepatic or sub-phrenic). A digital rectal exam to rule out the pelvic abscess and CT scan to localize intra-abdominal abscess. Treatment includes re-exploration vs. radiological guided percutaneous drainage
  • Drugs: Diagnosis of exclusion includes rash and peripheral eosinophilia

Delayed Fever

Fever after more than 4 weeks.

  • Skin and soft tissue infections (SSTI)
  • Viral infections

The above differential diagnosis is for causes that categorized based on timing. However, there are many other causes that may have specific signs on physical exam and occur after specific surgery that are not included in the above differential.


Initial assessment includes general appearance, GCS, and vital signs to determine how sick is the patient.[5][6]

  • Airway, Breathing, Circulatory, Disability, Exposure (quick assessment to identify and simultaneously provide appropriate management)
  • Check patient notes (the type of procedure, timing of the procedure, intraoperative complications, anesthesia records, patient comorbidities, last ward rounds)
  • Check patient Intake and Output (including the type of stools, if the patient with type 7 stools rule out Clostridium difficile enterocolitis)
  • Check patient orders (is the patient being treated with antibiotics or not, receiving deep vein thrombosis prophylaxis or not)
  • System based assessment (pulmonary, cardiac, gastrointestinal, urinary)
  • Sites of infection that are visible (i.e., skin for bedsores, cellulitis, vascular access sites)
  • Beside tests should monitor vital signs. If the patient is hypotensive, venous blood gas is needed to measure serum lactate. It will guide fluid resuscitation; if patient is tachycardic, bedside ECG might be important to confirm their rhythm, might rule out myocardial infarction; oxygen saturation 96% to 98% in patients with healthy lungs or 89% to 92% in carbon dioxide retaining patients, for example, COPD patients; monitor blood glucose levels because high blood glucose levels point towards septic response; urinalysis to rule out urinary tract infection
  • Blood tests: WBC, CRP especially if trending upward might point towards a septic response, hemoglobin level would point toward the oxygen-carrying capacity of the blood, liver function tests to rule out liver injury, coagulation parameters, and platelets to rule out disseminated intravascular coagulation, renal function to rule out kidney injury or electrolyte abnormalities
  • Microbiology: Cultures (blood, urine, wound, and sputum if producing it), if suspecting line sepsis (blood culture from the line, remove the line and send the tip to the lab)
  • Imaging: Chest x-ray (prove or rule out pneumonic process), abdominal imaging (ultrasound, CT scan to rule out collections)
  • Venous doppler of the legs to rule out Deep Vein Thrombosis

Treatment / Management

Treatment can include oxygen, fluid balance, intravenous fluids, and a urinary catheter, or antibiotics.

  • Drugs: antibiotics, analgesia, antiemetics
  • Incentive Spirometry
  • Venous thromboembolism prophylaxis (low molecular weight heparin and wearing pneumatic stocking)
  • Escalation (relay information to a senior health professional and ask for further advice from  infectious disease physician)

Differential Diagnosis

  • Pneumonia
  • Pulmonary embolus
  • Wound infection
  • Urinary tract infection
  • Transfusion reaction
  • Sinusitis


In most patients, postoperative fever is due to a benign cause and resolves spontaneously. Patients who have atelectasis recover quickly once they are started on incentive spirometry and/or chest physical therapy. Patients with deep vein thrombosis and pulmonary embolism usually have a low-grade fever that resolves within a few days of treatment. The prognosis is worse for patients who have anastomotic leaks or bowel obstruction.


  • Undiagnosed infection can cause sepsis and even death
  • prolonged hospitalization



Infectious disease

Deterrence and Patient Education

Patients who undergo general anesthesia should be advised to use incentive spirometry to prevent atelectasis, which is a common cause of postoperative fever.

Enhancing Healthcare Team Outcomes

Post-operative fever is a common occurrence on all surgical floors. Because there are so many causes of fever, the problem is usually managed by a multidisciplinary team of healthcare professionals. The nurse is probably the first person who monitors the patient and discovers the fever. In order to know the cause, the nurse should first check the wound site, auscultate the lungs and assess for deep vein thrombosis. Other causes of the post-operative fever may be a urinary tract infection, an intravenous line (thrombophlebitis) or sepsis. Once the fever has been noted, the health care provider should be notified, and the workup depends on patient presentation and the day of the fever. If atelectasis is suspected, a chest x-ray may be ordered, blood and urine culture for sepsis and a urinary tract infection and duplex ultrasound if a deep vein thrombus is suspected. The key is to examine the patient as it may provide a clue to the cause. [7][8](Level V)


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Postoperative Fever - Questions

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What is the most likely cause of postoperative fever within the first 48 hours?

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A 50-year-old female is admitted after elective open abdominal surgery. On post-operative day 3, she develops a fever to 37.9 degrees Celsius and a dry cough. Wound is clear. Chest X-ray shows small bilateral basilar infiltrates. Three sets of two bottles for blood cultures are drawn. One is positive for Staphylococcus epidermis and five are negative. What is the most likely diagnosis?

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A 55-year-old male known to have long-standing hypertension and diabetes mellitus with coronary artery disease underwent coronary artery bypass grafting 1 hour ago for 3 vessel disease. The operative course was uneventful. The patient was on cardiopulmonary bypass for 100 minutes. The patient is currently in a cardiac intensive care unit on a ventilator on synchronized intermittent mandatory ventilation with same settings since arrival. The chest-x-ray upon admission to the intensive care unit showed correct position of the endotracheal tube with adequate ventilation of the lungs. He has a urinary catheter in place with adequate urine output of approximately 1 milliliter per hour. His sternotomy wound is covered by a transparent dressing with no redness seen, or fluctuation felt. The mediastinal drain had an output of 30 milliliters of sanguineous fluid over the last hour. His blood pressure is 100/60 mmHg and heart rate 100 beats per minute. Since you are the resident on call, the nurse informs you that the patient has a fever of 39 degrees Celsius (102.2 degrees Fahrenheit). Labs done on arrival are significant for WBC count 16 x 10^9 per liter. He has received cefazolin 2 grams intravenously while receiving anesthesia for his operation but none after the procedure. Which of the following is the most likely cause of his fever?

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A 70-year-old female with end-stage renal disease secondary to long-standing diabetes mellitus with nephropathy is scheduled for hemodialysis. She has had a right-sided radio-cephalic arteriovenous fistula created 1 month ago. On exam, there is no thrill palpated over the fistula, and no bruit is heard by the stethoscope. Doppler ultrasound confirms lack of maturation with associated thrombosis in the fistula. Due to her high BUN and creatinine, it is decided to place a tunneled central venous catheter. The patient had started to receive hemodialysis 3 times a week. 2 months later she presents with fever, chills, and nausea, however, denies any other symptoms related to pulmonary, gastrointestinal or urinary systems. Vital signs include temperature 39 degrees Celsius, heart rate 105 beats per minute, blood pressure 100/50 mmHg, respiratory rate 18 per minute, and oxygen saturation 100 percent on room air. Physical exam is unremarkable. There is no redness, induration or swelling at the catheter exit site or more than 2 centimeters proximal to it along the tunnel track. White blood cell count is 14 x 10^9 per liter. You suspect catheter-related bloodstream infection. Your diagnosis is confirmed by positive blood cultures from a peripheral vein as well as from the tunneled catheter growing the same organism with blood cultures from the central catheter growing 2 hours earlier than from the peripheral vein and also having 3 times higher colony forming unit counts. In which of the following case scenarios would the catheter not require immediate removal?

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Postoperative Fever - References


Pergialiotis V,Sinanidis I,Louloudis IE,Vichos T,Perrea DN,Doumouchtsis SK, Perioperative Complications of Cesarean Delivery Myomectomy: A Meta-analysis. Obstetrics and gynecology. 2017 Dec     [PubMed]
Saltzman BM,Mayo BC,Bohl DD,Frank RM,Cole BJ,Verma NN,Nicholson GP,Romeo AA, Evaluation of fever in the immediate post-operative period following shoulder arthroplasty. The bone     [PubMed]
Serraino C,Elia C,Bracco C,Rinaldi G,Pomero F,Silvestri A,Melchio R,Fenoglio LM, Characteristics and management of pyogenic liver abscess: A European experience. Medicine. 2018 May     [PubMed]
Mayo BC,Haws BE,Bohl DD,Louie PK,Hijji FY,Narain AS,Massel DH,Khechen B,Singh K, Postoperative Fever Evaluation Following Lumbar Fusion Procedures. Neurospine. 2018 Jun     [PubMed]
Dodamani MH Jr,Kumar RR,Parkhi M,Basher R, Rare cause of fever of unknown origin: gastrointestinal stromal tumour. BMJ case reports. 2018 Mar 28     [PubMed]
Koutserimpas C,Nikitakis N,Skarpas A,Lada M,Papachristou E,Velimezis G, Epidural abscess imitating recurrent pilonidal sinus: a case report. Il Giornale di chirurgia. 2017 May-Jun     [PubMed]
Toba M,Moriwaki M,Oshima N,Aiso Y,Shima M,Nukui Y,Obayashi S,Fushimi K, Prevention of surgical site infection via antibiotic administration according to guidelines after gynecological surgery. The journal of obstetrics and gynaecology research. 2018 Sep     [PubMed]
Shastri N, Intravenous acetaminophen use in pediatrics. Pediatric emergency care. 2015 Jun     [PubMed]


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